Research Objectives
Develop and apply unstructured mesh numerical methods for magnetohydrodynamics (MHD) simulations.
Computational Approach
The MHD equations are discretized using finite element or finite volume methods on a two-dimensional unstructured mesh of triangular and quadrilateral cells. The mesh generation and discretization routines are packaged as a C++ class library, which encapsulates and hides the finite element code from the calling program, written in FORTRAN. Discretization in the third spatial dimension is on a regular mesh using either finite difference or spectral methods. Codes have been run on the NERSC C-90. A parallel version is under development.
Accomplishments
The MH3D++ code has been improved and is being used in applications. The code is an unstructured mesh version of the Princeton Plasma Physics Laboratory MH3D code, which calls the unstructured mesh class library. Pellet simulations are initialized with stable MHD equilibria. Introducing the pellet produces an unbalanced force, which causes the pellet to move outward (to the right) as well as spreading out along the magnetic field, until a new equilibrium is reached
Significance
An unstructured mesh provides two important advantages over conventional numerical approaches. It allows the mesh to conform to complicated boundary shapes, permits the mesh to be aligned with the magnetic field, and permits high resolution near important features, These advantages allow three-dimensional MHD simulations in magnetic field configurations with complex geometry, such as tokamaks with divertors. The pellet simulations mentioned in the previous paragraph are important for tokamak fuelling, particularly for the proposed International Tokamak Engineering Reactor (ITER).
Publications
Strauss, H. R. 1996. Edge-localized mode simulations in divertor tokamaks. Phys. Plasmas 3:1.
Park, W., Z. Chang, E. Fredrickson, G. Y. Fu, N. Pomphrey, H. R. Strauss, and L. E. Sugiyama. 1996. 3D simulation studies of tokamak plasmas using MHD and extended- MHD models. F1-CN-64/D2-2, Sixteenth IAEA Fusion Energy Conference, Montreal.
URL
Penetration of a fuel pellet, localized in three dimensions, into a tokamak.